RESUMEN
The complete nucleotide sequences for 6 strains of the West Nile fever virus were determined. For the first time the complete nucleotide sequences of the Indian isolate and Krsn190 strain, that is the most far phylogenetically from all isolates known at present time were established. The scheme for separation of virus variants into 4 groups and criteria for determination the group to which the isolate belongs are suggested.
Asunto(s)
Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/clasificación , Animales , Variación Genética , Humanos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Filogenia , Proteínas del Envoltorio Viral/genética , Virus del Nilo Occidental/genéticaRESUMEN
West Nile virus is a mosquito borne flavivirus endemic over a large geographic area including Africa, Asia, and the Middle East. Although the virus generally causes a mild, self-limiting febrile illness in humans, it has sporadically caused central nervous system infections during epidemics. An isolate of West Nile virus was obtained from a pool of four male Culex univittatus complex mosquitoes while we were conducting an investigation of Rift Valley fever along the Kenya-Uganda border in February-March 1998. This represents the first field isolation of West Nile virus from male mosquitoes and strongly suggests that vertical transmission of the virus occurs in the primary maintenance mosquito vector in Kenya. A phylogenetic analysis of the complete amino acid sequence of the viral envelope glycoprotein demonstrated a sister relationship with a Culex pipiens mosquito isolate from Romania made in 1996. This unexpected finding probably reflects the role of migratory birds in disseminating West Nile virus between Africa and Europe.
Asunto(s)
Culex/virología , Transmisión Vertical de Enfermedad Infecciosa , Insectos Vectores/virología , Fiebre del Nilo Occidental/transmisión , Virus del Nilo Occidental/inmunología , Secuencia de Aminoácidos , Animales , Antígenos Virales/análisis , Secuencia de Bases , Chlorocebus aethiops , Cartilla de ADN/química , ADN Viral/química , Electroforesis en Gel de Agar , Femenino , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Kenia/epidemiología , Datos de Secuencia Molecular , Filogenia , ARN Viral/química , ARN Viral/aislamiento & purificación , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Células Vero , Proteínas del Envoltorio Viral/química , Proteínas del Envoltorio Viral/genética , Fiebre del Nilo Occidental/epidemiología , Fiebre del Nilo Occidental/inmunología , Fiebre del Nilo Occidental/virología , Virus del Nilo Occidental/clasificación , Virus del Nilo Occidental/genéticaRESUMEN
In late summer 1999, an outbreak of human encephalitis occurred in the northeastern United States that was concurrent with extensive mortality in crows (Corvus species) as well as the deaths of several exotic birds at a zoological park in the same area. Complete genome sequencing of a flavivirus isolated from the brain of a dead Chilean flamingo (Phoenicopterus chilensis), together with partial sequence analysis of envelope glycoprotein (E-glycoprotein) genes amplified from several other species including mosquitoes and two fatal human cases, revealed that West Nile (WN) virus circulated in natural transmission cycles and was responsible for the human disease. Antigenic mapping with E-glycoprotein-specific monoclonal antibodies and E-glycoprotein phylogenetic analysis confirmed these viruses as WN. This North American WN virus was most closely related to a WN virus isolated from a dead goose in Israel in 1998.